Switch operating device for use with an over center diaphragm switch contact assembly with contact ramp camming surface

ABSTRACT

An operating device for use with an over center diaphragm switch contact assembly which includes a contact supporting board, a fixed contact, and an over center diaphragm contact resiliently deformable from a first position spaced apart from said fixed contact to a second position in electrical contact therewith. The operating device includes a guide plate having a slot therein and a knob element slidably received in the slot. The knob element includes a ramp surface which slidably, frictionally engages the surface of the guide plate proximal the diaphragm contact and a nib portion which slidably engages the diaphragm contact and arranged such that sliding movement of the knob element longitudinally within the slot operates the diaphragm contact from its first position to its second position. The ramp surface of the knob element maintains the diaphragm contact in electrical contact with the fixed contact whereby the operating device converts the resilient diaphragm contact assembly into a bistable &#39;&#39;&#39;&#39;on-off&#39;&#39;&#39;&#39; switch.

United States Patent [1 1 Forrest 1 1 SWITCH OPERATING DEVICE FOR USEWITH AN OVER CENTER DIAPHRAGM SWITCH CONTACT ASSEMBLY WITH CONTACT RAMPCAMMING SURFACE [75] Inventor: John W. Forrest, West Acton, Mass.

[73] Assignee: Bowman/Ali, Inc., Acton, Mass.

[22] Filed: May 2, 1973 1211 Appl. No.: 356,631

[52] US. Cl. 200/328; 200/159 B; 200/153 LA; 200/60; 200/157 [51] Int.Cl. HOih 9/22 [58] Field of Search 200/159 B, 166 G, 166 PC. 200/5 A, 5R, 153 LA, 169 PB, 157, 60, 239,

[56] References Cited UNITED STATES PATENTS 1,592,225 7/1926 Pieper200/157 2,992,307 7/1961 Reifel 200/166 G 3,725,907 4/1973 Boulanger200/5 A FOREIGN PATENTS OR APPLICATIONS 1,225,262 9/1966 Germany 200/169PB [451 May 27, 1975 Primary E.raminerRobert K. Schaefer AssistantExaminerGerald P. Tolin [57] ABSTRACT An operating device for use withan over center dia phragm switch contact assembly which includes acontact supporting board, a fixed contact, and an over center diaphragmcontact resiliently deformable from a first position spaced apart fromsaid fixed contact to a second position in electrical contact therewith.The operating device includes a guide plate having a slot therein and aknob element slidably received in the slot, The knob element includes aramp surface which slidably, frictionally engages the surface of theguide plate proximal the diaphragm contact and a nib portion whichslidably engages the diaphragm contact and arranged such that slidingmovement of the knob element longitudinally within the slot operates thediaphragm contact from its first position to its second position. Theramp surface of the knob element maintains the diaphragm contact inelectrical contact with the fixed contact whereby the operating deviceconverts the resilient diaphragm contact assembly into a bistableon-off" switch.

7 Claims, 3 Drawing Figures SWITCH OPERATING DEVICE FOR USE WITH AN OVERCENTER DIAPHRAGM SWITCH CONTACT ASSEMBLY WITH CONTACT RAMP CAMMINGSURFACE BACKGROUND OF THE INVENTION l. Field of the Invention Thepresent invention relates to miniaturized electrical switches and inparticular to an operating device for use with a monostable, over centerdiaphragm switch contact assembly, the operating device enablingoperation of the diaphragm contact assembly as a bistable on-off switch.

2. Description of the Prior Art Over center diaphragm switch contactassemblies are well known. Such switch assemblies are mechanicallysimple, reliable in operation, and can be fabricated in multiple switchassemblies which are exceptionally thin and compact. Correspondingly,this type of switch has proven well suited for use in miniaturizedelectronic equipment such as portable, hand held calculators. Such apush button keyboard switch assembly is disclosed in US. Pat. No.3,684,842, issued to Boulanger.

However, this type of switch assembly, because the diaphragm contactsused therewith are resilient, deformable elements, is inherently adaptedfor use in applications requiring a toggle type switch, that is, aswitch which is normally open and remains closed only so long as theoperator device associated therewith is held. This characteristic isdesirable for many applications of the over center diaphragm switchcontact assemblies. Nonetheless, most miniaturized electronic equipmentutilizing such switches also requires the use of bistable or on-off typeswitches. Correspondingly, it has heretofore been necessary to providetwo separate types of switch assemblies in such equipment to provideboth toggle and bistable type switches thereby adding to the expense andcomplexity of such equip ment.

SUMMARY OF THE INVENTION Broadly, the present invention is an operatordevice for use with an over center diaphragm switch contact assembly,the operator enabling the use of such a switch assembly as an on-off orbistable switch. The operator is adapted for use in an over centerdiaphragm switch contact assembly which includes a contact supportingboard, a fixed contact, an over center diaphragm contact resilientlydeformable from a first position spaced apart from the fixed contact toa second position in electrical contact therewith and means for makingelectrical connections thereto. The operator device comprises a rigidguide plate fixedly mounted in generally parallel, spaced apartrelationship to the diaphragm contact. The plate is provided with anelongated slot therein disposed in registry with the diaphragm contact.A manually operable knob element is provided having a guide portionslidably engaging the surface of the guide plate proximal to thediaphragm contact, a nib portion protruding from the guide portion andslidably engaging the diaphragm contact. and a tab portion which isslidably received through the slot for longitudinal movement forwardlyand rearwardly therein. The knob element further is provided with a rampsurface that is angled forwardly and downwardly with respect to the tabportion and which frictionally, slidably engages the aforementionedproximal surface of the guide plate. Longitudinal movement of the tabforwardly in the slot produces simultaneous downward movement of theknob element thereby operating the diaphragm contact from its first toits second positions. The ramp surface, because it frictionally engagesthe aforementioned proximal surface of the guide plate, maintains theknob element in its forward position thereby maintaining the switch inits closed position.

In a specific embodiment of the invention, the guide portion of the knobhas a width which is greater than the width of the slot. The knobelement is made of an electrically common non-conductive material. Thetab may have a length about equal to the length of the slot and isprovided with a notch therein on its forwardly disposed edge, the rampsurface being the lower surface of the notch.

In yet another specific embodiment of the invention, a thin film oflubricious plastic is disposed between the knob element and thediaphragm contact, the knob element nib portion having rounded edgedwhereby it slides smoothly on the surface of the plastic film.

It is therefore an object of the invention to provide an operatingdevice for use with an over center diaphragm switch contact assemblywhich enables operation of the assembly as a bistable switch.

It is another object of the invention to provide such an operator whichis simple in construction and provides a highly reliable bistableswitch.

It is still another object of the invention to provide such an operatorwhich includes a ramp surface which frictionally maintains the operatorand, thereby the switch, in an on position.

Another object of the invention is to provide such an operator adaptedfor use in multiple over center diaphragm switch assemblies.

It is yet another object of the invention to provide such an operatorwhich provides an exceptionally thin and compact bistable switchassembly BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and otherfeatures and objects of this invention and the manner of attaining themwill become more apparent and the invention itself will be bestunderstood by reference to the following description of an embodiment ofthe invention taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a sectionalized side plan view of the operator device of thepresent invention in combination with an over center diaphragm switchcontact assembly;

FIG. 2 is a top plan view of the knob element of the invention; and

FIG. 3 is an end plan view of the knob element.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,there is shown an operator device 10 in combination with an over centerdiaphragm switch contact assembly 12. Assembly 12 includes a supportingplate 16 and an aperture plate 18 having therethrough a circular opening20, plate 18 being fixedly bonded to plate 16 whereby opening 20 definesa circular recess 22 therewith.

Plate 16 may be a conventional printed circuit board which is made froma suitable fiber reinforced resin and having a multiplicity ofconductive circuit elements 24 formed thereon by conventional techniqueswell known to those skilled in the art.

A plurality of electrically conductive support elements 26 are securedto plate 16 adjacent the periphery of recess 22. Elements 26 may beformed of a stiff wire material into a generally U shape with the legs28 thereof extending downwardly through plate 16 and being mechanicallyand electrically coupled to the conducting elements 24 by soldering asat 30.

A fixed contact 32, generally diskshaped. is secured within recess 22adjacent the center thereof. Contact 32 may be made of a suitable thin,electrically conduc tive material and, preferably, is goldplated. Thecentral portion of contact 32 is upwardly indented as at 34 to therebyform a relatively small raised portion 36 in the center thereof.

An upwardly (as viewed in FIG. 1) concave, diskshaped contact 38 havinga diameter about equal to the diameter of recess 22 is received withinthe latter upon support elements 26. Contact 38 is made of a resilient,electrically conductive metal, preferably gold-plated, and is deformedfrom a flat shape to provide the concave shape thereof. Contact 38 is inelectrical contact with support elements 26 and thereby also withconducting elements 24. It will be apparent to those skilled in the artthat, by reason of the concave deformation of contact 38, contact 38will operate in an over center or oil can" manner whereby it can betoggled between its raised position shown in solid lines in FIG. 1 to asecond position shown in dotted lines in FIG. 1. It will be observedthat contact 38 is vertically spaced apart with respect to contactportion 36 when in its first or solid line position and is in electricalcontact therewith when in its second or deformed position shown indotted lines of FIG. I.

A guide plate 40 is mounted in vertically spaced apart relationship tosupport member 14. Guide plate 40 is made of a rigid, self-supportingmaterial such as sheet steel and may be supported in its illustratedposition by any suitable means (not shown). An elongated, rectangularslot 42 is formed through guide plate 40 in vertical registry withcontact 38.

Operator device further includes a knob element 43 having a guideportion 44 which is generally rectangular in shape and has a widthgreater than the width of slot 42. Preferably, guide portion 44 isprovided with an upstanding flange portion 46 adjacent the rearwardlydisposed edge 48 thereof, flange portion 46 slidably engaging theundersurface 50 of guide plate 40. Flange 46 has the same width as guideportion 48. A nib portion 52 is provided adjacent the center of guideportion 48, nib portion 52 extending downwardly from guide portion 48and slidably engaging contact 38. Preferably, nib portion 52 is circularin cross-section and has smoooth, rounded corners as at 54.

Upstanding from guide portion 44 is a tab portion 56. Tab portion 56 hasa generally rectangular crosssection and is slidably received throughslot 42. The upper edge 58 of tab portion 56 is serrated as shown tofacilitate engagement thereof with the fingertip. The forward edge 60 oftab portion 56 is provided with a notch 62 extending rearwardlytherefrom (to the left as viewed in FIG. 1). The lower (as viewed inFIG. 1) wall of notch 62 is tapered to provide a ramp surface 64 whichextends forwardly and downwardly with respect to tab portion 56.

In operation, operator device 10 is normally in its rearwardly (asviewed in FIG. 1) disposed position within slot 42, operator 10 beingshown in this position in solid lines in FIG. 1. Under these conditions,contact 38 is in its spaced apart position with respect to contact 34,this being shown in the solid lines in FIG. 1, whereby there is noelectrical contact between contacts 34 and 38.

To operate switch contact assembly 12 to an on position, Le, a positionwherein contact 38 is in electrical contact with contact 34, knobelement 43 is pressed downwardly and forwardly. Downward movement ofknob element 43 forces nib portion 52 against contact 38 deforming samedownwardly to the position thereof illustrated in dotted lines in FIG.1, thereby placing contact 38 in electrical contact with contact 34.Simultaneously, movement of tab portion 56 forwardly (as viewed inFIG. 1) slides ramp surface 64 against the undersurface 50 of guideplate 40. As tab portion 56 is moved forwardly, ramp surface 64 iswedged against undersurface 50 thereby maintaining nib portion 52 inpositive engagement with contact 38.

When finger pressure is removed from tab portion 56, ramp surface 64,because it frictionally engages the undersurface 50 of guide plate 40,maintains knob element 43 in the position thereof illustrated in dottedlines in FIG. 1 thereby maintaining switch contacts 38 and 34 inelectrical contact.

To turn the switch off, knob element 43 is pushed rearwardly (to theleft as viewed in FIG. 1) until the rear edge 66 of tab portion 56engages the rear edge 68 of slot 42. When finger pressure is removed,knob element 43 will move upwardly under the resilient force generatedby contact 38. Because ramp surface 64 has now moved out of contact withundersurface 50 of guide plate 40, knob element 43 is able to move upwardly thereby breaking the electrical contact between contacts 38 and34.

In a specific embodiment of the invention, a thin film 70 of a tough,lubricious, and flexible plastic may be positioned in overlyingengagement with plate 18 and contact 38 as shown. Film 70 enhances thesliding contact between nib portion 52 and contact 38 thereby enhancingthe durability and ease of operation of the switch assembly. Preferably,knob element 43 is made from a non-conductive plastic.

From the above description, it will be seen that, because the electricalcontact between contacts 38 and 34 is maintained by ramp surface 64,minor wear of ramp surface 64 will not deteriorate operation of theswitch assembly since additional forward movement thereof willcompensate for this wear. Further, because of the small angle of rampsurface 64, a positive frictional engagement between surface 64 andundersur face 50 positively maintains the switch in an on position. Itis thus seen that the operator device of the present invention convertsthe normal toggle action or over center diaphragm switch into a bistableswitch without any modification of the over center switch contactassembly. The operator is simple in construction, and self-compensatesfor wear. The switch action is positive and electrical Contact betweencontacts 34 and 38 is insured. The operator thus enables the fabricationof a bistable switch which is compatible with the over cen ter diaphragmswitch widely used in miniaturized electronic equipment, the operatorbeing an integrated part of the switch assembly, requiring the samerelative amount of space, and not requiring the use of differentcomponents.

It will further be apparent that variations in the switch assembly canbe made without departing from the scope of the invention. For example,ramp surface 64 may be formed as a part of the undersurface 50 of guideplate 40. Other positionings of the ramp surface 64 to effect the samemechanical operation. i.e., the simultaneous forward and downwardmovement of the knob element 44 will be apparent to those skilled in theart.

In a specific embodiment of the invention, the ramp surface 64 is formedat an angle of about degrees with respect to the guide portion 48.

While there have been described above the principles of this inventionin connection with specific apparatus, it is to be clearly understoodthat this description is made only by way of example and not as alimitation to the scope of the invention.

What is claimed is:

1. For use in an over center diaphragm switch contact assembly whichincludes a Contact supporting board, a fixed contact, an over centerdiaphragm contact resiliently deformable from a first position spacedapart from said fixed contact to a second position in electrical contacttherewith, and means for making electrical connections thereto, a switchoperating device comprising a rigid guide plate fixedly mounted ingenerally parallel, spaced-apart relationship to said board anddiaphragm contact, said plate having an elongated slot therein disposedin registry with said dia phragm contact, and a manually operable knobelement having a guide portion positioned between said plate anddiaphragm contact and slidably engaging the surface of said plateproximal said diaphragm Contact, said guide portion having a widthgreater than the width of said slot, a nib portion protruding from saidguide portion and slidably engaging said diaphragm contact, a tabportion slidably received through said slot for longitudinal movementforwardly and rearwardly therein, and a ramp surface angled forwardlyand downwardly from said tab portion to said guide portion, said rampfrictionally, slidably engaging said proximal surface upon longitudinalmovement of said tab portion forwardly in said slot thereby causingsimultaneous downward movement of said device, said diaphragm contactbeing operated from said first to said second position thereof inresponse to said downward movement, said ramp surface frinctionallymaintaining said diaphragm contact in said second position.

2. The device of claim 1 wherein said guide portion further includes anupwardly extending flange adjacent the rearwardly disposed edge thereof,said flange having a width greater than the width of said slot andslidably engaging said proximal surface.

3. The device of claim 1 further comprising a thin, flexible filmoflubricious plastic material overlying said diaphragm contact, said nibportion slidably engaging said film.

4. The device of claim 3 wherein said knob element is made of anelectrically, non-conducting material.

5. The device of claim 1 wherein said tab portion has a length generallyequal to the length of said slot, there being a notch in the forwardlydisposed end of said tab portion, said ramp surface being the surface ofsaid notch proximal said guide portion.

6. The device of claim 1 wherein said nib portion, when said tab portionis in the rearwardly disposed position thereof, engages said diaphragmContact at a point displaced from the center thereof, said nib portion,when said tab portion has been moved forwardly, engaging said diaphragmportion at a point adjacent the center thereof.

7. The device of claim 6 wherein said nib portion is cylindrical, thedistal edges thereof being rounded and smooth.

1. For use in an over center diaphragm switch contact assembly whichincludes a contact supporting board, a fixed contact, an over centerdiaphragm contact resiliently deformable from a first position spacedApart from said fixed contact to a second position in electrical contacttherewith, and means for making electrical connections thereto, a switchoperating device comprising a rigid guide plate fixedly mounted ingenerally parallel, spaced-apart relationship to said board anddiaphragm contact, said plate having an elongated slot therein disposedin registry with said diaphragm contact, and a manually operable knobelement having a guide portion positioned between said plate anddiaphragm contact and slidably engaging the surface of said plateproximal said diaphragm contact, said guide portion having a widthgreater than the width of said slot, a nib portion protruding from saidguide portion and slidably engaging said diaphragm contact, a tabportion slidably received through said slot for longitudinal movementforwardly and rearwardly therein, and a ramp surface angled forwardlyand downwardly from said tab portion to said guide portion, said rampfrictionally, slidably engaging said proximal surface upon longitudinalmovement of said tab portion forwardly in said slot thereby causingsimultaneous downward movement of said device, said diaphragm contactbeing operated from said first to said second position thereof inresponse to said downward movement, said ramp surface frinctionallymaintaining said diaphragm contact in said second position.
 2. Thedevice of claim 1 wherein said guide portion further includes anupwardly extending flange adjacent the rearwardly disposed edge thereof,said flange having a width greater than the width of said slot andslidably engaging said proximal surface.
 3. The device of claim 1further comprising a thin, flexible film of lubricious plastic materialoverlying said diaphragm contact, said nib portion slidably engagingsaid film.
 4. The device of claim 3 wherein said knob element is made ofan electrically, non-conducting material.
 5. The device of claim 1wherein said tab portion has a length generally equal to the length ofsaid slot, there being a notch in the forwardly disposed end of said tabportion, said ramp surface being the surface of said notch proximal saidguide portion.
 6. The device of claim 1 wherein said nib portion, whensaid tab portion is in the rearwardly disposed position thereof, engagessaid diaphragm contact at a point displaced from the center thereof,said nib portion, when said tab portion has been moved forwardly,engaging said diaphragm portion at a point adjacent the center thereof.7. The device of claim 6 wherein said nib portion is cylindrical, thedistal edges thereof being rounded and smooth.